US4298115A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Time-lapse indicator
Assignee: MICRO-CIRCUITS COMPANY A CORP OF MICH
•
Filing: 1979-02-09
•
Granted: 1981-11-03
•
Expires: 1999-02-09
Abstract
Abstract A time-lapse indicator in which an electrically conducting, fluid-absorbent layer is initially separated from an activating fluid. When the indicator is activated the fluid flows into the absorbent layer, thereby changing the electrical conductivity of the absorbent layer. The fluid may be retained by a receptacle having a rupturable wall portion in a layer paralleling said absorbent layer and the rupturable wall portion may be a frangible layer between the liquid and the absorbent layer, which is broken when the indicator is activated. A time delay layer may also be included between the frangible layer and the absorbent layer to control the rate of flow of the liquid into the absorbent layer and thereby prolong the effective operation of the indicator following activation thereof.
Inventors
- 👤 Robert F. Bradley
- 👤 Lindell P. Bradley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 21:08
CPC Classifications
G; G07; G07C; G07C1/00; G07C1/02; G04; G04F; G04F13/00; G07C1/30
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
137 words
A time-lapse indicator comprising a layer of fluid-absorbent material, a particulated electrically conductive material disposed in said fluid-absorbent layer for rendering said layer electrically conductive, a means for holding a fluid in close proximity to said absorbent layer, a fluid migrating at substantially a predetermined rate to said absorbent layer from said holding means, said fluid when absorbed by said absorbent layer varying the conductivity of the absorbent layer in proportion to the degree of absorption of the fluid by the absorbent layer, with the degree of change in conductivity of said absorbent layer being related to the time duration of exposure of said fluid absorbent layer to said fluid to determine the time-lapse following commencement of the fluid transmittal, and a rupturable barrier means separating said fluid from said absorbent layer until said indicator is activated.
Claim 2
Dependent Claim
137 words
A time-lapse indicator comprising a layer of fluid-absorbent material, a particulated electrically conductive material disposed in said fluid-absorbent layer for rendering said layer electrically conductive, a means for holding a fluid in close proximity to said absorbent layer, a fluid migrating at substantially a predetermined rate to said absorbent layer from said holding means, said fluid when absorbed by said absorbent layer varying the conductivity of the absorbent layer in proportion to the degree of absorption of the fluid by the absorbent layer, with the degree of change in conductivity of said absorbent layer being related to the time duration of exposure of said fluid absorbent layer to said fluid to determine the time-lapse following commencement of the fluid transmittal, and a rupturable barrier means separating said fluid from said absorbent layer until said indicator is activated.
Claim 3
Dependent Claim
36 words
A time-lapse indicator as defined in claim 1 in which a retarding layer is disposed between said fluid and said absorbent layer for controlling the migration of fluid to said absorbent layer at the predetermined rate.
Claim 4
Dependent Claim
30 words
A time-lapse indicator as defined in claim 2 in which said fluid exists as a solid in its stored and unactivated form and fluidifies upon commencement of a timing cycle.
Claim 5
Dependent Claim
33 words
A time-lapse indicator as defined in claim 2 in which droplets of said fluid are encased in rupturable beads and said rupturable beads are positioned in a layer parallel to said retarding layer.
Claim 6
Dependent Claim
40 words
A time-lapse indicator as defined in claim 1 in which a receptacle contains said fluid in a layer parallel with said absorbent layer, and the rupturable barrier means is a frangible layer separating said fluid layer from said absorbent layer.
Claim 7
Dependent Claim
16 words
A time-lapse indicator as defined in claim 5 in which an envelope substantially encloses said layers.
Claim 8
Dependent Claim
24 words
A time-lapse indicator as defined in claim 5 in which a porous retarding layer is disposed between said fluid layer and said absorbent layer.
Claim 9
Dependent Claim
24 words
A time-lapse indicator as defined in claim 6 in which a porous retarding layer is disposed between said fluid layer and said absorbent layer.
Claim 10
Dependent Claim
16 words
A time-lapse indicator as defined in claim 8 in which said particulate material is silver powder.
Claim 11
Dependent Claim
36 words
A time-lapse indicator as defined in claim 6 in which said envelope is flexible and puncture-proof and said frangible layer may be punctured by the depression of a blunt instrument on the surface of said indicator.
Claim 12
Dependent Claim
41 words
A time-lapse indicator as defined in claim 1 in which said fluid absorbent layer has spaced electrodes thereon for passing a current through said layer between said electrodes, and said current is used to measure the conductivity of said absorbent layer.
Claim 13
Dependent Claim
16 words
A time-lapse indicator as defined in claim 1 in which said particulate material is silver powder.
Claim 14
Dependent Claim
30 words
A time-lapse indicator as defined in claim 1 in which said fluid exists as a solid in its stored and unactivated form and fluidifies upon commencement of a timing cycle.
Claim 15
Dependent Claim
29 words
A time-lapse indicator as defined in claim 1 in which said fluid is conductive and as it is absorbed by said absorbent layer enhances the conductivity of said layer.
Claim 16
Dependent Claim
28 words
A time-lapse indicator as defined in claim 14 in which said rupturable barrier means is a relatively brittle frangible layer separating said fluid layer from said absorbent layer.
Claim 17
Dependent Claim
41 words
A time-lapse indicator as defined in claim 15 in which a retarding layer is disposed between said frangible layer and said absorbent layer to assist in controlling the migration of said conductive fluid to said absorbent layer at the predetermined rate.
Claim 18
Dependent Claim
33 words
A time-lapse indicator as defined in claim 1 in which droplets of said fluid are encased in rupturable beads, and said rupturable beads are positioned in a layer parallel to said absorbent layer.
Claim 19
Dependent Claim
29 words
A time-lapse indicator as defined in claim 1 in which droplets of said fluid are encased in rupturable beads, and said rupturable beads are dispersed throughout said absorbent layer.
Claim 20
Dependent Claim
37 words
A time-lapse indicator as defined in claim 1 in which said fluid is retained in a receptacle having a rupturable portion and said rupturable portion consists of a frangible layer between said fluid and said absorbent layer.
Claim 21
Dependent Claim
41 words
A time-lapse indicator as defined in claim 19 in which a retarding layer is disposed between said frangible layer and said fluid absorbent layer to control the rate of migration of the fluid to said absorbent layer at the predetermined rate.
Claim 22
Dependent Claim
40 words
A time-lapse indicator as defined in claim 19 in which said receptacle is disposed along one edge of said indicator, and said fluid is forced out of said receptacle and flows over said absorbent layer upon activation of said indicator.
References Cited (Backward Citations)
US3273683A
Cited
US2589983A
Cited
US2626381A
Cited
US2746745A
Cited
US2917814A
Cited
US3046786A
Cited
US3045179A
Cited
US3620677A
Cited
US3295088A
Cited
US3480402A
Cited
US3479864A
Cited
US3539470A
Cited
US3603880A
Cited
US3511608A
Cited
US3510263A
Cited
US3520124A
Cited
US3581703A
Cited
US3679978A
Cited
US3839857A
Cited
US4125822A
Cited
US3954011A
Cited
US3998307A
Cited
US4057029A
Cited
US4086475A
Cited
US4100490A
Cited
US4229813A
Cited
US4206838A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-11-02 | 1985-05-04 | 1985-11-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-11-02 | 1989-05-04 | 1989-11-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-11-02 | 1993-05-04 | 1993-11-03 | $7700.00 | Window Closed / Lapsed |